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PubMed2005

[Effect of caffeic acid, seopoletin and scutellarin on rat retinal neurons in vitro].

OBJECTIVE: To observe the effect of caffeic acid, seopoletin and scutellarin on rat retinal neurons in vitro and explore neuroprotection in glaucoma of Erigeron breviscapus. METHOD: The retinal of 18 post-natal 2-3 days Sprague-Dawley rats were dissociated into cell suspension with trypsin digestion. The cell suspension was implated in 96-well culture plates covered with hyaluronic acid and laminin in each well. After culturing for 3 days, caffeic acid, seopoletin and scutellarin were added to the cultures, continue to culture 2 days. Then, the A of living cells in each well was tested by MTT colorimetric microassay. Some of the 5-day culture cells were identified by Nissel technique. RESULT: Most of the living cells were retinal neurons by Nissel identification. The number of living cells increased significantly in high concentrations of caffeic acid, seopoletin and scutellarin compared with control group (P < 0.05, P < 0.01). CONCLUSION: caffeic acid, seopoletin and scutellarin can all promote retinal neurons to live in vitro, with caffeic acid being most effective.

Animals↗
PubMed2004

[Caffeic acid (CA) protects cerebellar granule neurons (CGNs) from apoptosis induced by neurotoxin 1-methyl-4-phenylpyridnium (MPP+)].

OBJECTIVE: To assess the effects of caffeic acid (CA) on MPP(+)-induced cerebellar granule neurons (CGNs) apoptosis. METHODS: CGNs were pretreated with caffeic acid at 55, 110 and 220 micromol/L for 6 h, then treated with 100 micromol/L MPP(+) for 24 h (concentration-effect relationship). In addition CGNs were pretreated with caffeic acid at 110 micromol/L for 0 h, 6 h, 12 h, and 24 h, respectively, then treated with 100 micromol/L MPP(+) for 24 h (time-response relationship). Besides, after treatment with MPP(+) for 24 h, CGNs were incubated with caffeic acid at 55, 110 and 220 micromol/L, respectively. Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and caspase-3 activity was assayed by caspase-3 fluorometric assay kit. RESULTS: MTT assay revealed that caffeic acid significantly inhibited cell viability decrease induced by MPP(+), and caspase-3 fluorometric assay showed that caffeic acid efficiently suppressed caspase-3 activation in CGNs induced by MPP(+). CONCLUSION: Caffeic acid (CA) can significantly protect CGNs from apoptosis induced by MPP(+) and may provide a useful therapeutic strategy for the treatment of Parkinson's disease.

1-Methyl-4-phenylpyridinium↗
PubMed2004

Antioxidant caffeic acid derivatives from leaves of Parthenocissus tricuspidata.

Five caffeic acid derivatives; methyl ester of caffeoylglycolic acid (1), dimethyl ester of caffeoyltartaric acid (2), dimethyl ester of caffeoyltartronic acid (3), monomethyl ester of caffeoyltartronic acid (4), methyl ester of caffeic acid (5), and some other secondary metabolites including; quercetin, quercetin 3-O-beta-D-glucuronide methyl ester, kaempferol, 3,5,7,4'-O-tetramethylkaempferol, beta-sitosterol glucoside, 2alpha-hydroxyursolic acid and 2,24-dihydroxyursolic acid, have been isolated and characterized. All the isolated compounds were characterized with the help of NMR spectroscopy and mass spectrometry. Structure of compound 3 was also confirmed by a single X-ray crystallographic technique. Isolates were evaluated for antioxidant activities and most of the tested compounds were found to be potent in DPPH free radical scavenging (IC50 = 4.56-14.17 microg/mL) and superoxide anion scavenging (IC50 = 0.58-7.39 microg/mL) assays.

Animals↗
PubMed1993

The oxidation of caffeic acid derivatives as model reaction for the formation of potent gonadotropin inhibitors in plant extracts.

Synthetic caffeic acid derivatives, substoichiometrically oxidized with KMnO4, exhibit antigonadotropic activity against pregnant mare serum gonadotropin (PMSG) to a greater degree than caffeic acid itself. Inhibitory compounds, formed after an oxidation of caffeic acid and its derivatives are bound to PMSG dependent on their concentration to result in hormone-inhibitor complexes. These PMSG-inhibitor complexes exhibited little or no biological activity, depending on the structure of the inhibitor. The substoichiometric oxidation with KMnO4 led to the corresponding unstable o-quinones as first products. The complete oxidation reaction could be divided into an initial KMnO4-dependent step followed by a manganese-catalyzed autoxidation, which was accompanied by a pronounced oxygen uptake from the solution. The HPLC analysis after an oxidation of caffeic acid derivatives led to product patterns with strong similarities to those of caffeic acid in the respective product UV spectra, suggesting the formation of compounds with similar structures.

Animals↗
PubMed1979

Colorimetric determination of caffeic acid in plant materials.

A new colorimetric method is described for determining caffeic acid content in plant materials. Caffeic acid is separated by thin layer chromatography from the alcoholic extract, and color is developed using 0.5% aqueous thiosemicarbazide solution under alkaline conditions. The absorbance is read at 475 nm. Lambert-Beer's law is obeyed in the concentration range 0.37-17.5 micrograms caffeic acid/mL. The method is reproducible and has been applied to the estimation of caffeic acid in carrot roots.

Caffeic Acids↗
PubMed2005

Caffeic acid inhibits vascular smooth muscle cell proliferation induced by angiotensin II in stroke-prone spontaneously hypertensive rats.

Epidemiological studies have linked the consumption of phenolic acids with reduced risk of cardiovascular diseases. In the present study, we sought to investigate whether caffeic acid, a phenolic acid which is abundant in normal diet, can antagonize angiotensin II (Ang II)-induced vascular smooth muscle cell (VSMC) proliferation in stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto (WKY) rats, and if so, to elucidate the underlying cell signaling mechanisms. We exposed VSMCs to Ang II and caffeic acid and found that caffeic acid significantly inhibited intracellular superoxide anion generation (decreased from 127 +/- 6.3% to 100.3 +/- 6.6% of the control cells) and the cell proliferation induced by Ang II. Furthermore, caffeic acid significantly abolished the tyrosine phosphorylation of JAK2 (decreased from 7.4 +/- 0.6-fold to 2.4 +/- 0.6-fold at 2 min) and STAT1 (decreased from 1.8 +/- 0.2-fold to 0.5 +/- 0.1-fold at 2 min) and the phosphorylation of ERK1/2 (decreased from 99.2 +/- 10.2-fold to 49.8 +/- 10.9-fold at 2 min) that were induced by Ang II. These effects of caffeic acid were consistent with the inhibition of the proliferation of VSMCs by DPI, an NADPH oxidase inhibitor, and by AG-490, a JAK2 inhibitor. In conclusion, our findings suggest that caffeic acid attenuates the proliferative reaction of VSMCs to Ang II stimulation in both SHRSP and WKY rats by inhibiting the generation of reactive oxygen species and then partially blocking the JAK/STAT signaling cascade and the Ras/Raf-1/ERK1/2 cascade.

Angiotensin II↗
PubMed1984

Caffeic acid is a selective inhibitor for leukotriene biosynthesis.

.eukotrienes are significantly involved in immunoregulation and in a variety of diseases, including asthma, inflammation and various allergic conditions. They are initially biosynthesized by 5-lipoxygenase from arachidonic acid, which can also be metabolized to prostaglandin endoperoxide by cyclooxygenase. The specific inhibitors for 5-lipoxygenase would be useful not only as tools for investigating the regulation mechanism of leukotriene biosynthesis, but also as drugs for clinical use. Although recently a few selective inhibitors have been reported, most of them are difficult to obtain, since they are new compounds. We found that caffeic acid, which is one of the most common reagents, is a selective inhibitor for 5-lipoxygenase and therefore for leukotriene biosynthesis. The inhibitory effect of its methyl ester on 5-lipoxygenase (ID50 = 4.8 X 10(-7) M) was stronger than that of caffeic acid itself (ID50 = 3.7 X 10(-6) M). Caffeic acid inhibited 5-lipoxygenase in a non-competitive manner. Caffeic acid and its methyl ester did not inhibit prostaglandin synthase activity at all, at least up to 5 X 10(-4) M, but rather stimulate at higher doses. The biosynthesis of leukotriene C4 and D4 in mouse mast tumor cells was also inhibited completely with 10(-4) caffeic acid. Besides, caffeic acid had little effect on arachidonic acid metabolism in platelet at less than 1 X 10(-5) M, but at higher doses it showed a definite inhibitory effect, i.e., thromboxane B2, HHT (12(S)-hydroxy-5,8,10-heptadecatetraenoic acid) and 12-HETE (12(S)-hydroxy-5,8,10,14-eicosatetraenoic acid) syntheses were inhibited 33, 40 and 80% at 1 X 10(-4) M, respectively. Platelet aggregation induced by arachidonic acid was also inhibited by caffeic acid at high dose, while platelet aggregation induced by ADP is not influenced by caffeic acid at all. The observations on caffeic acid and its derivatives may contribute to leukotriene research.

Animals↗
PubMed2003

Regioselectivity of glucosylation of caffeic acid by a UDP-glucose:glucosyltransferase is maintained in planta.

Caffeic acid is a phenylpropanoid playing an important role in the pathways leading to lignin synthesis and the production of a wide variety of secondary metabolites. The compound is also an antioxidant and has potential utility as a general protectant against free radicals. Three glucosylated forms of caffeic acid are known to exist: the 3- O - and 4- O -glucosides and the glucose ester. This study describes for the first time a glucosyltransferase [UDP-glucose:glucosyltransferase (UGT)] that is specific for the 3-hydroxyl, and not the 4-hydroxyl, position of caffeic acid. The UGT sequence of Arabidopsis, UGT71C1, has been expressed as a recombinant fusion protein in Escherichia coli, purified and assayed against a range of substrates in vitro. The assay confirmed that caffeic acid as the preferred substrate when compared with other hydroxycinnamates, although UGT71C1 also exhibited substantial activity towards flavonoid substrates, known to have structural features that can be recognized by many different UGTs. The expression of UGT71C1 in transgenic Arabidopsis was driven by the constitutive cauliflower mosaic virus 35 S (CaMV35S) promoter. Nine independent transgenic lines were taken to homozygosity and characterized by Northern-blot analysis, assay of enzyme activity in leaf extracts and HPLC analysis of the glucosides. The level of expression of UGT71C1 was enhanced considerably in several lines, leading to a higher level of the corresponding enzyme activity and a higher level of caffeoyl-3- O -glucoside. The data are discussed in the context of the utility of UGTs for natural product biotransformations.

Arabidopsis↗
PubMed1982

Protein-polyphenol reactions. 1. Nutritional and metabolic consequences of the reaction between oxidized caffeic acid and the lysine residues of casein.

1. Studies were made on the lysine content of casein reacted with caffeic acid oxidized aerobically under alkaline conditions of enzymically with tyrosinase (EC 1. 14. 18. 1). 2. Loss of fluorodinitrobenzene (FDNB)-reactive lysine was rapid at pH 10 and increased with time and the temperature of the reaction, with concentration of caffeic acid and with the oxygenation of the mixture. In presence of the enzyme mushroom tyrosinase, maximum reduction of reactive lysine occurred at pH 7 and was dependent on the reaction time and on the concentration of caffeic acid. 3. Reaction of alpha-formyl-LO-[U-14C]lysine with caffeic acid at pH 10 showed the rapid formation of five reaction products which appeared to polymerize gradually as the reaction progressed. 4. The nutritionally available lysine content of the casein-caffeic acid mixtures, as assayed with rats, was reduced after both alkaline and enzyme reactions, as were faecal digestibility, net protein ratio and net protein utilization. Biological value however was not reduced. 5. In metabolic studies using goat milk casein labelled with L-[3H]lysine and reacted with caffeic acid in the same way, the lysine-caffeoquinone reaction products were not absorbed by the rat but were excreted directly in the faeces. 6. The importance of the reaction of proteins with caffeoquinone and chlorogenoquinone (formed by the oxidation of caffeic and chlorogenic acids respectively) is discussed in relation to the production of sunflower protein, leaf protein and other vegetable-protein concentrates.

Animals↗
PubMed2006

Caffeic acid protects hydrogen peroxide induced cell damage in WI-38 human lung fibroblast cells.

Cytoprotective effect of caffeic acid (3,4-dihydroxy cinnamic acid) on human lung fibroblast (WI-38) cells against hydrogen peroxide induced damage was investigated. Caffeic acid was found to scavenge intracellular reactive oxygen species, and 1,1-diphenyl-2-picrylhydrazyl radical, and thus prevented lipid peroxidation. The caffeic acid protected cell damage of WI-38 cells exposed to hydrogen peroxide (H(2)O(2)), via the activation of extracellular signal regulated kinase protein. Caffeic acid increased the activity of catalase and its protein expression. Hence, from the present study, it is suggestive that caffeic acid protects WI-38 cells against H2O2 damage by enhancing the cellular antioxidant activity.

Caffeic Acids↗
PubMed1999

Degradation of cyanidin 3-glucoside by caffeic acid o-quinone. Determination of the stoichiometry and characterization of the degradation products.

Caffeic acid o-quinone (CQ) was prepared by oxidation of caffeic acid with o-chloranil in organic media. The reaction between the purified CQ and cyanidin 3-glucoside (Cy 3-glc, o-diphenolic anthocyanin) was monitored by HPLC, and quantitative analyses were performed to establish the stoichiometry of the reaction. The results indicate that Cy 3-glc is degraded by a coupled oxidation mechanism with integration of CQ into the degradation products. The ratio of degraded Cy 3-glc to CQ incorporated into the condensation products was approximately 2.0. No brown products could be detected, only a slight orange color. Moreover, the addition of purified polyphenol oxidase to the slightly colored media resulted in the disappearance of the caffeic acid formed from the reaction of coupled oxidation (Cy 3-glc/CQ) and the formation of brown polymers. The degradation products were isolated by gel filtration on Sephadex G-25. The UV-vis spectra and chemical analysis (acidic hydrolysis) of the degradation products suggest that they resulted from the condensation of caffeic acid and Cy 3-glc. HPLC analysis showed that the partial purified fraction contained a mixture of complex condensation products.

Anthocyanins↗